1. Technical Field of the Invention
This invention relates to fluid injection and monitoring apparatus for the introduction of one or more fluid additives to a gaseous or liquid stream and for monitoring the stream.
2. Description of the Prior Art
In for example the oil extraction industry, it is known practice to inject additives into a gas or liquid stream in a pipe line to accomplish "conditioning" of the oil, adding various chemicals to enhance desired properties or counteract undesired properties. At present, the usual practice is to inject the additive through a branch pipe opening radially or tangentially into the main pipe line. This however creates a weakness in the pipe line string which is eroded by the high-fluid flow rates in the main pipe line, leading to possible catastrophic failure. In an alternative, a branch pipe line terminates in a probe or projecting tube fed by a branch pipe, the probe extending some distance into the main pipe line flow passage to discharge the additive into the main flow. An example of such an arrangement is shown in GB 1,601,403, where a radially extending probe introduces an additive into a fluid stream, upstream with respect to a static mixer. Such a probe is again vulnerable to erosion leading to failure.
It is also known from GB 2015360-A to provide an injector in mixing a apparatus, comprising a diametrically extending tube extending across a flow passage, with discharge orifices directed to the downstream side of the tube, to introduce the additive in the lee of the tube. The discharge orifices are arranged in two sets, each set discharging into one of a pair of split fluid streams, and this arrangement is disclosed only as part of a static mixing apparatus.
It is also desirable to be able to monitor the condition of the fluid stream to, for example, control the introduction of additives in response to stream conditions.